During an automated manufacturing process, a multilayer sample of material, such as a multilayer wafer, may be inspected using conventional inspection systems to determine the overall thickness of the multilayer sample and to determine thicknesses of the various layers. During the automated manufacturing process, while the composition of each of the layers is often known, the order of the layers, and the corresponding orientation of the layers, is often unknown.
For example, during an automated manufacturing process, a multilayer wafer may have a silicon layer and a silicon dioxide layer, and the multilayer wafer may need to be oriented with the silicon layer on top to allow the silicon layer to be ground down during the automated manufacturing process to a specific thickness. Therefore, a conventional inspection system may be positioned above the multilayer wafer to inspect the multilayer wafer as it travels through the automated manufacturing process in order to measure the thickness of the top silicon layer to verify that the silicon layer is successfully ground down to the specific thickness. In this example, however, the multilayer wafer may inadvertently become turned upside down during the automated manufacturing process such that the silicon layer, which should be on the top to be exposed for grinding down, ends up on the bottom. While the conventional inspection system may be able to determine that the multilayer wafer has a top layer and a bottom layer, and may be able to determine the thicknesses of the top layer and the bottom layer, the conventional inspection system may be unable to determine which of the top and bottom layers is the silicon layer and which is the silicon dioxide layer.
In another example, during an automated silicon wafer thinning and packaging process, the detailed structure of a multilayer wafer may be unknown. In this automated process, identifying a remaining silicon thickness may involve determining a thickness of: the lowest layer of the structure if the multilayer wafer resides on grinding tape, the second-lowest layer if the multilayer wafer resides on dicing tape, or the third-lowest layer if the multilayer wafer resides on Die Attachment Film (DAF) tape attached to dicing tape. The exact thickness of the remaining silicon may be an important parameter for heat transfer in modern semiconductor devices. While a conventional inspection system may be able to determine that the multilayer wafer has multiple layers, and may be able to determine the thicknesses of the layers, the conventional inspection system may be unable to determine the compositions and order of the layers. For example, a conventional inspection system may be unable to determine the thickness of a particular layer of a multilayer wafer, such as the layer that is intended to be the lowest layer of the multilayer wafer.
Therefore, conventional inspection systems may be unable to correctly identify differences in the compositions of different layers of a multilayer sample during an automated manufacturing process. This inability of conventional inspection systems may be result in undetected problems with the order of the layers in a multilayer sample, and the corresponding orientation of the layers, such as undetected upside-down multilayer samples, resulting in manufacturing defects during the automated manufacturing process.
The subject matter claimed in this disclosure is not limited to embodiments that solve any disadvantages or that operate only in environments such as those described above. Rather, this background is only provided to illustrate one example technology area where some embodiments described in this disclosure may be practiced.